matplotlib graph to plot values and variance
You have currently stored your numbers as strings causing matplotlib to treat your variable as categorical, hence the y-axis is not ordered as expected. Before plotting you should therefore first convert them to integers like this:

x = [float(i.replace(",", ".")) for i in dev_x]


You can then use plt.plot(x) once again to plot the values, this should give you the following plot:



Edit:

Using the csv file you've provided, I am using the following code to read in the data and create the plot:

import matplotlib.pyplot as plt
import pandas as pd

# Read in csv file
df = pd.read_csv("DATA.csv")
# Set figure size
plt.figure(figsize=(15, 5))
# Create plot
plt.plot(df["DATA"])


This should give the following plot: