a. Spice exports from Africa fluctuated wildly over the period. 

There were ...

b. The development of new products fell gradually. 

There was ...

c. There has been a noticeable decrease in research investment.

Research ...

d. The purchases of tickets dropped significantly last month.

There was ...

e. On the Internet, the number of sites rose significantly. 

There was ...

f. There was a sudden decrease in the sale of mangos.

The sale ...
g. At the theme park, there were very slight fluctuations in the number of visitors. 
The number...