What is appropriate data structure to work on my data in C++?

I have n subjects for each subject we have 2 types of measurement at different time points with different lengths. All the values are double, and time points are int.

For example,

subject 1

Measure 1:

Value: 1.1, 0.25, 0.7

Time: 0, 12, 35

Mesure 2:

Value: 2.2, 1.8, 0.95,0.4

Time: 3, 10,33,40

Subject 2:

Measure 1:

Value: 1.4, 1.25, 0.9,1.7,1.1

Time: 0, 12, 35,40,45

Mesure 2:

Value: 0.2, 1.1, 0.35

Time: 7, 15,23

Should I vector of vector or there are some way to store these data and access easily?