Following a record year for affordable housing creation, Boston Mayor Martin Walsh still isn’t satisfied.

“Because of our growth and economic success, we’ve become a city of high housing costs,” Walsh said Tuesday morning at Bisnow’s Boston Affordable Housing Conference. “We need to make sure our city is an opportunity for everyone who wants to live here.”

Boston’s Inclusionary Development Policy drove the creation of 546 new units of affordable housing in the city in 2018, or 21% of the program’s overall production since it began in 2000. Walsh said the program, which requires developers of multifamily projects with 10 or more units to create on-site or off-site affordable housing or contribute to the Inclusionary Development Policy Fund, has been successful, but he is still looking to adjust it to make room for more housing creation.

“[546] is a good number. We obviously want to see bigger numbers, but that’s a good number,” Walsh said. “We got more affordable units without slowing down development in the ongoing boom.”

The IDP calls for 13% of a multifamily development to be reserved for affordable housing. Developers in the past have cautioned against raising the IDP rate, saying it would make it less enticing to do business in the city. The Walsh administration was warned there would be pushback against its housing plan, the mayor said, but he added developers have been open to the list of affordable housing strategies, including raising the IDP rate from 13% to 18%.

“Not everyone was happy, but not everyone was mad,” Walsh said.

The Walsh administration earlier this year announced $26M in new and recommended funding from a variety of city agencies to create and preserve 515 units of housing in seven neighborhoods and fund additional affordable housing programming. The mayor also plans to recommend a record level of city investment for the preservation of affordable housing when he presents his proposed 2020 fiscal budget Wednesday, he said at Tuesday’s event.

“The bottom line is we have to use every tool, idea and partnership we have to meet our housing needs,” Walsh said.