I have the following line of code which shows me percent change in US county population from 2000 to 2010. I need a percentile_cont formula to determine median of the percent change in county population overall. This is the code i am using to get the percent changes:

SELECT c2010.geo_name, c2010.state_us_abbreviation AS state, c2010.p0010001 AS pop_2010, c2000.p0010001 AS pop_2000, c2010.p0010001 - c2000.p0010001 AS raw_change, round( (CAST(c2010.p0010001 AS numeric(8,1)) - c2000.p0010001)/ c2000.p0010001 * 100, 1 ) AS pct_change FROM us_counties_2010 c2010 INNER JOIN us_counties_2000 c2000 ON c2010.state_fips = c2000.state_fips AND c2010.county_fips = c2000.county_fips AND c2010.p0010001 <> c2000.p0010001 ORDER BY pct_change DESC;