C++ and vector dynamic expansion

How Does the capacity changes as the size increases?  Well, this simple test code and chart will clear up the questions.

// This program demonstrates the vector size member function.
#include <iostream>
#include <vector>
#include<cmath>
#include<fstream>
 
using namespace std;
 
int main() {
 ofstream outFile;
 outFile.open("c:\\temp\\analysis.csv");
 vector<int> values;
 cout << typeid(values).name() << endl;
 outFile << "size, capacity, diff, count" << endl;
 // Put a series of numbers in the vector.
 for (int count = 0; count < 20; count++) {
  values.push_back(count * 2);
  outFile << values.size() << "," << values.capacity() << ","
   << abs((int)(values.size() - values.capacity()))
   << "," << count << endl;
 }
 vector<int> temp;
 for (int i : values)         //even copying based on size value will increment capacity beyond size  
  temp.push_back(i);
 values.shrink_to_fit();     //size will match capacity
 outFile.close();
 return 0;
}

This same kind of effect can be observed with string as well.

// This program demonstrates the vector size member function.
#include <iostream>
#include <vector>
#include<cmath>
#include<fstream>
#include<string>
 
using namespace std;
 
int main() {
 ofstream out("c:\\temp\\out.csv");
 string item = "a";
 out << "count,size,capacity" << endl;
 cout <<"1,"<<item.size() << "," << item.capacity() << "," << endl;
 for (int i = 2; i < 1000; i++) {
  item += "a";
  out <<i<<"," << item.size() << "," << item.capacity() << "," << endl;
 }
 out.close();
 return 0;
}