why Normal Distribution with Histogram not matching?

Hi, I have a vector of 30189 rows and 300+ columns. All of them with normal distribution. When I try to plot the Normal distribution and histogram of one column, the curve crest is ~2 (max y axis) but when I put the histogram, they reach like 4000 in the y axis making the distribution curve to be way too small to be seen. Why? Below I left figures.

for Distribution_tap=1:pt
pd=fitdist(Cp(:,Distribution_tap),'Normal');
x_values=min(Cp(:,Distribution_tap)):0.01:max(Cp(:,Distribution_tap));
y_value=pdf(pd,x_values);
hold on
plot(x_values,y_value,'LineWidth',2);
histogram(Cp(:,Distribution_tap),30)
end

First figure shows the distribution only

This is when I add the histogram

Third figure shows the data is normally distributed

Answer 1

[Steven Lord]

Use:

histogram(Cp(:,Distribution_tap),30, 'Normalization', 'pdf')

Answer 2

[Ive J]

This is because histogram shows frequency of your sample, while PDF plots the density. Of course you can change the way histogram behaves:

x = randn(1000, 1);
pd = fitdist(x, 'Normal');
x_values = min(x):0.01:max(x);
y_values = pdf(pd, x_values);

hold on
plot(x_values, y_values, 'LineWidth', 2)
histogram(x, 'Normalization', 'pdf')