As is clearly illustrated in the chart, some remarkable changes/differences have taken place in recent years with (主题词). The number/proportion of (主题词) was roughly xx, approximately xx in (时间/地点)/for(因素), and around xx in (时间/地点)/for(因素).
What accounts for the noteworthy scenario? It is not difficult for us to point out some factors responsible for it. To begin with, the phenomenon is closely related to the rapid development of our economy and huge improvement of people's living standard. More importantly，the change/difference is enhanced and promoted by the government's better policies. Finally, the change/difference has a lot to do with the turning of the people's attitude towards and outlook on life.
As the society further develops and people's outlooks gradually turn, the phenomenon is bound to continue for decades of years in the future. As far as I am concerned, it's a positive(negative) trend and should be stimulated (limited), for it is beneficial (harmful)not merely to individuals but also to the whole society.