How to compare 'population=*' in Tilemill CartoCSS?

Question

The Problem

Comparing population with CartoCSS in my TileMill project doesn't work unless I specifically cast population to a numeric type in my Postgres query. The problem with that, is that it is not stable. I can do this without problems for The Netherlands, but there apparently is a population tag as 27 813 in Germany. This leads to Postgis Plugin: ERROR: invalid input syntax for type double precision: "27 813".

This lead me to believe that population is a string/text type in the Postgres database. Looking at the default osm2pgsql style file that I used during import confirms my suspicion that it is returned as a string.

The Postgresql Query

( SELECT way, place AS type, name, z_order, population
  FROM planet_osm_point
  WHERE place in ('country', 'state', 'city', 'town', 'village', 'hamlet', 'suburb', 'neighbourhood', 'locality', 'isolated_dwelling','city_block','borough','islet','island')
  ORDER BY population DESC NULLS LAST
) AS data

A snippet from the CartoCSS

Question

Is there a right way to compare the population, without casting it or getting casting problems? Is casting it the right way to do it?