Took my quite a while... but I did it! For the agricultural density, since I couldn't find the data on the internet, I used simple math and found the number of farmers and number of arable land. Then I just divided the two and found the agricultural density...
Sources:
http://data.worldbank.org/indicator/EN.POP.DNST
https://www.google.com.tw/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CBwQFjAA&url=http%3A%2F%2Fwww.umsl.edu%2F~naumannj%2FGeography%25201002%2520articles%2FIntroduction%2FPhysiologic%2520Population%2520Density%2520for%2520Each%2520of%2520the%2520World%27s%2520States.doc&ei=6JcqVIvqONW78gWZ1YDIAg&usg=AFQjCNFXRKrdR3nnL_zj-SF6Bl8ckRFfSA&bvm=bv.76477589,d.dGc
http://www.nationsencyclopedia.com/economies/Europe/Belgium-AGRICULTURE.html
http://data.worldbank.org/indicator/AG.LND.ARBL.ZS
https://www.cia.gov/library/publications/the-world-factbook/fields/2097.html
Sources:
http://data.worldbank.org/indicator/EN.POP.DNST
https://www.google.com.tw/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CBwQFjAA&url=http%3A%2F%2Fwww.umsl.edu%2F~naumannj%2FGeography%25201002%2520articles%2FIntroduction%2FPhysiologic%2520Population%2520Density%2520for%2520Each%2520of%2520the%2520World%27s%2520States.doc&ei=6JcqVIvqONW78gWZ1YDIAg&usg=AFQjCNFXRKrdR3nnL_zj-SF6Bl8ckRFfSA&bvm=bv.76477589,d.dGc
http://www.nationsencyclopedia.com/economies/Europe/Belgium-AGRICULTURE.html
http://data.worldbank.org/indicator/AG.LND.ARBL.ZS
https://www.cia.gov/library/publications/the-world-factbook/fields/2097.html