It's not official, but in all probability the AFL will expand its finals series to 10 teams next season when Greater Western Sydney joins the party and makes it an 18-team league.

Whether or not you like the proposed setup, one thing is for certain: this would be one of the highest percentages of teams making the finals of any elite league in the world.

An 18-team AFL, with 10 clubs making the finals, works out to 56 per cent. Only rugby league's English Super League is higher, with eight of fourteen teams - a whopping 57 per cent - making the finals.

The proposed AFL finals system would be the same as Major League Soccer in the United States, and higher than the NBA and the NHL (both 53 per cent) which are routinely criticised in the US for allowing too many teams into the post-season.

Keep in mind, however, that all US professional leagues - with the exception of the NFL - utilise playoff series, so first round matchups in the NBA and NHL could actually mean a total of seven games. The NBA and NHL playoffs drag on for months, while a new AFL system would only extend an extra week, from four to five.

When it comes to Australian sporting leagues, a 10-team AFL finals would be a slightly higher percentage than the A-League (55 per cent), a bit higher than the NRL (50 per cent), and much higher than the revamped Super Rugby competition (40 per cent).

Interestingly, the two most traditional American leagues, the NFL and MLB are the most stringent when it comes to the postseason. The NFL, probably the most successful domestic league in the world, only allows 38 per cent of its teams into the post-season, while MLB remains the most stingy of all league, with only eight of 30 teams (27 per cent) making the playoffs.

The AFL has said it will make a decision on the 2012 fixturing, including finals, sometime in June.

Leagues, teams and percentages

English Super League: 14 teams, eight make playoffs (57%)

Possible 2012 AFL: 18 teams, ten make finals (56%)

MLS: 18 teams, 10 make playoffs (56%)

A-League: 11 teams, six make finals (55%)

NBA: 30 teams, 16 make playoffs (53%)

NHL: 30 teams, 16 make playoffs (53%)

NRL: 16 teams, eight make playoffs (50%)

Japanese baseball: 12 teams, six make playoffs (50%)

Current AFL: 17 teams, eight make finals (47%)

Super Rugby: 15 teams, six make finals (40%)

NFL: 32 teams, 12 make playoffs (38%)

MLB: 30 teams, eight make playoffs (27%)