Using attendance "records" (some seem to be estimates) from the past season from http://www.worldfootball.net.

Top 20 Average Home Attendance:

1. Borussia Dortmund (Bundesliga) 80,297
2. Manchester United (Premier League) 75,207
3. FC Barcelona (La Liga) 71,958
4. Bayern München (Bundesliga) 71,000
5. Real Madrid (La Liga) 70,754
6. FC Schalke 04 (Bundesliga) 61,569
7. Arsenal FC (Premier League) 59,487
8. Bor. Mönchengladbach (Bundesliga) 52,239
9. Hertha BSC (Bundesliga) 51,889
10. Hamburger SV (Bundesliga) 51,825
11. VfB Stuttgart (Bundesliga) 50,498
12. Newcastle United (Premier League) 50,395
13. Manchester City (Premier League) 47,080
14. Eintracht Frankfurt (Bundesliga) 47,053
15. Atlético Madrid (La Liga) 46,746
16. Inter (Serie A) 46,246
17. Hannover 96 (Bundesliga) 45,635
18. Paris Saint-Germain (Ligue 1) 45,420
19. Liverpool FC (Premier League) 44,671
20. Seattle Sounders FC (MLS) 43,734

Top Leagues Average Home Attendance:

Canadian/US American Major League Soccer 2014

1 Seattle Sounders 43,734

2 Toronto FC 22,086

3 Los Angeles Galaxy 21,227

4 Portland Timbers 20,768

5 Vancouver Whitecaps 20,408

Argentine Primera División 2013/2014 (combining Torneo Inicial and Torneo Final)

1 River Plate 42,368

2 Rosario Central 38,368

3 Boca Juniors 37,895

4 Newell's Old Boys 37,158

5 Belgrano Córdoba 26,526

Brazilian Série A 2013

1 Cruzeiro EC 29,315

2 Flamengo RJ 26,350

3 Corinthians SP 25,168

4 São Paulo FC 23,024

5 Grêmio Porto Alegre 22,301

Mexican "Liga MX" Primera División 2013/2014 (combining Apertura and Clausura)

1 CF América 41,259

2 UANL Tigres 41,036

3 CF Monterrey 30,318

4 Deportivo Guadalajara 25,446

5 Atlas Guadalajara 22,852

English Premier League 2013/2014

1 Manchester United 75,207

2 Arsenal FC 59,487

3 Newcastle United 50,395

4 Manchester City 47,080

5 Liverpool FC 44,671

6 Chelsea FC 41,482

7 Sunderland AFC 41,090

8 Everton FC 37,732

9 Aston Villa 36,081

10 Tottenham Hotspur 35,808

German Bundesliga 2013/2014

1 Borussia Dortmund 80,297

2 Bayern München 71,000

3 FC Schalke 04 61,569

4 Bor. Mönchengladbach 52,239

5 Hertha BSC 51,889

6 Hamburger SV 51,825

7 VfB Stuttgart 50,498

8 Eintracht Frankfurt 47,053

9 Hannover 96 45,635

10 Werder Bremen 40,657

French Ligue 1 2013/2014

1 Paris Saint-Germain 45,420

2 Lille OSC 38,662

3 Olympique Marseille 38,129

4 Olympique Lyon 34,414

5 AS Saint-Étienne 30,390

6 FC Nantes 28,116

7 OGC Nice 22,913

8 Stade Rennes 19,524

9 Girondins Bordeaux 18,833

10 Stade Reims 15,558

Italian Serie A 2013/2014

1 Inter 46,246

2 SSC Napoli 40,918

3 AS Roma 40,083

4 AC Milan 40,061

5 Juventus 37,318

6 ACF Fiorentina 33,098

7 Lazio Roma 29,548

8 Sampdoria 22,102

9 Hellas Verona 21,206

10 Bologna FC 21,145

Spanish La Liga Primera División 2013/2014

1 FC Barcelona 71,958

2 Real Madrid 70,754

3 Atlético Madrid 46,746

4 Valencia CF 36,903

5 Athletic Bilbao 33,383

6 Real Betis 30,652

7 Sevilla FC 30,545

8 Elche CF 25,320

9 Real Sociedad 23,204

10 Málaga CF 21,551