Finance lease

Question in study test:
The building has a remaining useful life of 50 years. The lease term,
which would commence on 1 January 20X0, is for 30 years.

Answer:
The lease term is only for 60% (30 years/50 years) of the asset’s useful
life. This factor suggests that the lease is an operating lease.

One of the indicator of Finance lease is:
“The lease term is for the major part of the asset’s economic life.”
How to define major part? I was thinking 60% should be a major part.