MLS Stats (2017) League size: 22 teams Average-Age: 26,6 Years Number of players: 622 Foreign players: 327 Player(s) 52,6% NASL Stats (2017) League size: 8 teams Average-Age: 27,6 Years Number of players: 191 Foreign players: 105 Player(s) 55,0% USL Stats (2017) League size: 30 teams Average-Age: 24,1 Years Number of players: 874 Foreign players: 401 Player(s) 45,9% NWSL Stats (2017) League size: 10 teams Average-Age: ? Number of players: ? Foreign players: ? MASL (2016-2017) League size: 17 teams Average-Age: ? Number of players: ? Foreign players: ? Source: transfermarkt
For reference: EPL: 370/551, or 67.2%. Bundesliga: 276/535, or 51.6%. Serie A: 312/588, or 53.1%. La Liga: 198/478, or 41.4%. Eredivisie: 175/435, or 40.2%. LigaMX: 197/480, or 40.2%. What I'm wondering is if Canadians count as "foreign" players.
The six numerators and six denominators combined make 49.8%, which is close to MLS. Maybe Canadian players count as "foreign" unless they are on Canadian clubs. I think transfermarkt should use the same standard as MLS does.
Found this online... "A limited number of Canadians will now count as domestic players in Major League Soccer, the league announced Wednesday. The change was announced as part of a larger initiative taken together with the Canadian Soccer Association and officials working the league’s three Canadian teams in an attempt to improve youth development for Canada. Previously, Canadian players only counted as domestic in MLS if they played for one of the Canadian-based sides: Toronto FC, the Montreal Impact and Vancouver Whitecaps. Otherwise, Canadian players counted toward U.S.-based teams’ international player restrictions. But the rule change now will make any Canadian player domestic to U.S.-based sides provided he is a homegrown player who joined an MLS academy or CSA-approved youth club in the year prior to the year he turns 16 and that player’s first contract was with either an MLS or USL side. MLS added in its statement that it will work with the CSA to determine what teams fit the “approved youth club” designation and that a team does not need to be affiliated with an MLS team to qualify. Currently only nine players qualify. MLS also announced a Canadian-specific Generation Adidas program as part of the larger youth initiative. The league and CSA will work together to identify Canadian players who would then be signed to contracts and made available in the MLS SuperDraft."