Issue with y-ticks alignment in pandas bar chart

Question

here is the data and code that I'm using to plot the bar chart as shown in the output plot. The issue is with y-ticks, I need to have y-ticks aligned in a vertical manner such that they cover/coincides with all four bars. If we use rot = 'some int value' the ticks rotate, but they do not exactly align vertically covering four bars.

Polymer	Depth	Residual time
HPAM7030	50	1159
HPAM7030	100	1638
HPAM7030	200	2170
HPAM7030	500	2718
APAM7525	50	2040
APAM7525	100	3101
APAM7525	200	4176
APAM7525	500	5270

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
plt.style.use(['science', 'notebook', 'grid'])
df.pivot(index = 'Polymer', columns = 'Depth', values = 'Residual time').plot(kind='barh')
plt.title('Residual time of different polymers (2 year simulation)')
plt.ylabel("Type of Polymer")
plt.xlabel("Residual time (Days)")
plt.show()