Spending on leisure has witnessed

Over the past 30 to 40 years, spending on leisure has witnessed a strong increase. According to the annual family expenditure survey published in 1999 by the Office for National Statistics, the average household in the United Kingdom spent more on leisure than food, housing and transport for the very first time.

Source: "IELTS test".

I am confused about the word "witness" here. I think it means the following in Longman dictionary.
witness
TIME/PLACE
if a time or place witnesses an event, the event happens during that time or in that place
Recent years have witnessed the collapse of the steel industry.
However, the subject of the original is "spending on leisure". It is neither "time" nor "place".
Thanks.