A decade into the impact investing industry’s formal creation, the industry “is becoming increasingly established and professionalized, but also a market that is complex and diverse,” according to Amit Bouri, cofounder and chief executive of the Global Impact Investing Network.

GIIN’s latest annual survey, released Wednesday, shows that in 2016, 209 leading impact investors committed a total of $22.1 billion into 7,951 impact investments, and planned to increase capital invested this year by 17% and the number of investments by 20%.

Survey responses were collected between December and February. In total, the 209 investors managed nearly $114 billion in impact investing assets, a figure that serves as a best-available floor for the size of the impact investment market, according to GIIN.

GIIN recently reported that impact investors were using financial guarantees as a credit-enhancement tool to stimulate increased private-sector investment in solutions to a wide range of challenges.

Ninety-eight percent of respondents in the new annual survey said their investments had either met or exceeded their expectations for impact, and 91% expressed satisfaction with financial performance.

While 66% of respondents targeted risk-adjusted, market rates of return, 18% sought below-market-rate returns that were closer to market rate, and 16% looked for returns closer to capital preservation.

Roughly four out of five survey participants agreed that below-market-rate capital plays a valuable role in impact investing, including its ability to mitigate risk of investments to attract new investors, act as a bridge between philanthropy and market-rate capital, and capitalize opportunities that may never lend themselves to risk-adjusted returns.

The main sectors to which respondents allocated capital last year were housing (22%), energy (16%) and microfinance (12%). By geography, 40% of assets went to the U.S. and Canada, 14% to Europe, 10% to sub-Saharan Africa and 9% to Latin America and the Caribbean.

According to the survey, more and more brand-name asset managers and other financial firms are entering the impact investing space. Respondents expected this trend to help professionalize the market, bring in much-needed capital and enhance the credibility of impact investing.

However, they also associated the trend with a risk of mission drift or “impact dilution.” Half also felt that there was a risk of capital shifting away from smaller intermediaries.

Investors reported progress on several fronts in 2016, with 90% noting a growing abundance of professionals with relevant skillsets and 89% reporting greater availability of market research and data on products and performance.

Twenty-six percent of respondents said they tracked their impact investment performance to the U.N. Sustainable Development Goals, and 34% planned to do so in the near future.

According to GIIN, these goals have served as a rallying cry for many impact investors to link their investments to a broader international initiative.

Nearly all survey respondents said they measured the social and/or environmental performance of their impact investments, using a mix of proprietary metrics, qualitative information, IRIS-aligned metrics and other tools and frameworks.

As for challenges to impact investing industry development, about half of respondents reported a lack of appropriate capital across the risk/return spectrum.

They also reported that defining and segmenting the diverse industry remains an issue, as does the lack of suitable exit options.