Here are the results of queries on the latest (April 2021) FIDE rating list.
Interesting to note that Iceland is actually only in 2nd. I guess in the map in the question Monaco is too small to see. The first big country (population > 1 million) is Armenia in 5th. Russia, the country with the most GMs - 240, is only in 31st place. No sign in this list of China or India.
Country - GMs - GMsPerMillion
- Monaco - 3 - 79.4
- Iceland - 13 - 39.1
- Andorra - 2 - 27.9
- Faroe Islands - 1 - 20.3
- Armenia - 40 - 13.3
- Montenegro - 6 - 9.6
- Georgia - 30 - 8.0
- Croatia - 30 - 7.1
- Serbia - 50 - 7.0
- Latvia - 11 - 5.6
- Hungary - 53 - 5.4
- Slovenia - 11 - 5.3
- Israel - 44 - 5.2
- Macedonia - 10 - 4.8
- Bulgaria - 33 - 4.58
- Estonia - 6 - 4.57
- Czech Republic - 34 - 3.2
- Norway - 16 - 3.1
- Lithuania - 8 - 2.8
- Azerbaijan - 26 - 2.7
- Mongolia - 8 - 2.6
- Denmark - 14 - 2.5
- Cuba - 27 - 2.4
- Slovakia - 13 - 2.4
- Netherlands - 38 - 2.24
- Sweden - 22 - 2.23
- Bosnia Herzegovina - 8 - 2.1
- Ukraine - 87 - 2.0
- Belarus - 17 - 1.78
- Moldova - 6 - 1.68
- Russia - 240 - 1.64
- Scotland - 7 - 1.31
- Greece - 14 - 1.29
- Poland - 49 - 1.27
- Qatar - 3 - 1.24
- Spain - 57 - 1.23
- Germany - 95 - 1.17
- Switzerland - 9 - 1.08
- Romania - 21 - 1.06
- Turkmenistan - 5 - 1.05
- Austria - 9 - 1.03
- Kazakhstan - 15 - 0.85
- Belgium - 9 - 0.796
- France - 51 - 0.791
- Finland - 4 - 0.727
- Singapore - 4 - 0.723
- England - 36 - 0.679
- Paraguay - 4 - 0.584
- Uruguay - 2 - 0.575
- Uzbekistan - 17 - 0.548
When you look at GMs per thousand FIDE registered players the picture changes. Armenia moves to the top and China appears in the list at no. 5.
FullName - Players - GMs - GMSPerThousandPlayers
- Armenia - 1789 - 40 - 22.4
- Monaco - 136 - 3 - 22.1
- Qatar - 147 - 3 - 20.4
- Andorra - 151 - 2 - 13.2
- China - 3783 - 48 - 12.7
- Macedonia - 1048 - 10 - 9.54
- Georgia - 3377 - 30 - 8.88
- Cuba - 3080 - 27 - 8.77
- Israel - 5316 - 44 - 8.23
- Turkmenistan - 606 - 5 - 8.25
- Bulgaria - 4512 - 33 - 7.31
- Scotland - 994 - 7 - 7.04
- Uzbekistan - 2417 - 17 - 7.03
- Belarus - 2648 - 17 - 6.42
- Montenegro - 1031 - 6 - 5.82
- Iceland - 2244 - 13 - 5.79
- Ukraine - 15318 - 87 - 5.68
- United States - 18067 - 96 - 5.31
- Moldova - 1139 - 6 - 5.27
- Azerbaijan - 5223 - 26 - 4.98
- Serbia - 10151 - 50 - 4.93
- Hungary - 11116 - 53 - 4.77
- Netherlands - 8152 - 38 - 4.66
- Tajikistan - 232 - 1 - 4.31
- Vietnam - 2996 - 12 - 4.01
- England - 9464 - 36 - 3.80
- Canada - 4059 - 14 - 3.45
- Mongolia - 2331 - 8 - 3.43
- Latvia - 3284 - 11 - 3.35
- Paraguay - 1210 - 4 - 3.31
- Sweden - 6694 - 22 - 3.29
- Estonia - 1853 - 6 - 3.24
- Croatia - 9292 - 30 - 3.23
- Bosnia Herzegovina - 2794 - 8 - 2.86
- Russia - 96262 - 240 - 2.49
- Faroe Islands - 404 - 1 - 2.48
- Czech Republic - 14000 - 34 - 2.43
- Norway - 6671 - 16 - 2.4
- Germany - 39740 - 95 - 2.39
- Argentina - 10001 - 23 - 2.3
- Finland - 1781 - 4 - 2.245
- Slovenia - 5201 - 11 - 2.11
- Philippines - 6200 - 13 - 2.1
- Australia - 4824 - 10 - 2.07
- Romania - 10165 - 21 - 2.066
- Switzerland - 4528 - 9 - 1.99
- Denmark - 7074 - 14 - 1.98
- Kazakhstan - 8056 - 15 - 1.86
- Lithuania - 4575 - 8 - 1.75
- Poland - 28878 - 49 - 1.7