Given the task definition and input, reply with output. In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

What did former mayor Greg Nickels propose for the population increase?, Context: In recent years, the city has experienced steady population growth, and has been faced with the issue of accommodating more residents. In 2006, after growing by 4,000 citizens per year for the previous 16 years, regional planners expected the population of Seattle to grow by 200,000 people by 2040. However, former mayor Greg Nickels supported plans that would increase the population by 60%, or 350,000 people, by 2040 and worked on ways to accommodate this growth while keeping Seattle's single-family housing zoning laws. The Seattle City Council later voted to relax height limits on buildings in the greater part of Downtown, partly with the aim to increase residential density in the city centre. As a sign of increasing inner-city growth, the downtown population crested to over 60,000 in 2009, up 77% since 1990.
ways to accommodate this growth while keeping Seattle's single-family housing zoning laws