The pie charts compare the yearly expenditure of a UK school in 1981, 1991 and 2001.
Overall, the salaries for teachers accounted for the largest part over these three years constantly, while the cost of insurance was always the smallest part of all school spending over the same period of time.
Teachers’ salaries constituted 40% in 1981 the increased 10 percent after a decade, which means it became half part of total spending in 1991. After that, it slightly declined to 48% in 2001. On the other hand, same as human resource, money for other workers’ salaries gradually decreased every ten years, from 28% (in 1981) to 22% (in 1991) then reached at only 15% (in 2001).
Essential resources such as books shared the same proportion (15%) with furniture and equipment in 1981. In 1991, school spent more in books and much less in furniture and equipment by contrast. But after another 10 years later, resources like books only made up to only 9% of total school spending while the percentage of furniture and equipment increased to 20. 
The pie charts compare the yearly expenditure of a UK  
school
 in 1981, 1991 and 2001. 
Overall
, the salaries for teachers accounted for the largest part over these three years  
constantly
, while the cost of insurance was always the smallest part of all  
school
 spending over the same period of time.
Teachers’ salaries constituted 40% in 1981 the increased 10 percent after a decade, which means it became half part of total spending in 1991. After that, it  
slightly
 declined to 48% in 2001.  
On the other hand
, same as human resource, money for other workers’ salaries  
gradually
 decreased every ten years, from 28% (in 1981) to 22% (in 1991) then reached at  
only
 15% (in 2001).
Essential resources such as books shared the same proportion (15%) with furniture and equipment in 1981. In 1991,  
school
 spent more in books and much less in furniture and equipment by contrast.  
But
 after another 10 years later, resources like books  
only
 made up to  
only
 9% of total  
school
 spending while the percentage of furniture and equipment increased to 20.