The SP:LP ratio has been very consistent for those selling a home under $2,000,000 – you can expect to get pretty close to your asking price.  Above $2,000,000 is a different story.

Mortgage rates had averaged 3.99% in 2017. You can see how the lower-end buyers became less concerned about getting a discount as rates started rising in early 2018 (they reached 4.59% in May, 2018):

This is another place that listing agents manipulate the data. When marking their listings as sold, many will lower the list price to match the sales price in order to make it look like they sell their listings for ask.