I am sure india's rank was higher in average speed before Jio as nobody was using data network bcoz of its high price and now price crashed so usage spiked which is taxing carrier's network resource.
Don't expect stable 8 Mbps cellular data on the move, it will work if you have broadband connection in home but India has only 1 crore(mostly in cities) such users compared to 25 crore 3G/4G users, broadband ISP in rural or semi urban areas will give you max 2-3 mbps at an affordable price and more than 5 mbps will have a price such that that majority people cannot afford that luxury.
Alliance is charging Rs1350+ 18%GST for 9 Mbps here, I am 99.99% sure nobody here(along with 5-6 nearby village) will pay that much price so majority are on Rs400+18%GST pack which gives just 2 Mbps and that too is shared with neighbours so that people have to pay less, so actual speed will go somewhere around 100-150 Kbps in real usage