hubert:
It's mainly China, India, and in addition countries like Japan, Iran, or Korea. (Lately, I would also include Vietnam)
I think for now this is the case. However, there is certainly a renewed (or first time) presence of countries such as Myanmar, Philippines, Uzbekistan, Bhutan, Mongolia, and Indonesia. All of these countries are now actively pursuing nominations, often with extensive tentative lists. We also cannot forget Taiwan, as it seems a solution is on the horizon to include Taiwanese heritage sites.
On top of the regular nominations by China, India, Iran, Korea, Vietnam and Japan; these additional countries named above are all under-represented and include several sites we discussed in the Top 50 missing. It remains to be seen, if these countries can churn out high-quality nomination dossiers of deserving sites in the coming years.
Nevertheless, ultimately I believe each World Heritage Conference moving forward, especially by 2016, will be the norm (not the exception) to have more nominations from Asia than any other region.
General trend amongst countries with frequent nominations
Inscriptions since 2004 (last 10 years)
EUROPE Top 5 (41)
Italy: 11
Germany: 10
France: 9
Russia: 6
Spain: 5
*Nominations to be evaluated in 2014: 6
*Respective Tentative List: 136
ASIA Top 5 (45)
China: 16
Iran: 12
India: 6
Japan: 6
Korea (DPRK & ROK): 5
*Nominations to be evaluated in 2014: 6
*Respective Tentative List: 168