table from wikipedia

[snippsat]

You are a little on wrong track when you start to manually parse the table.
Change your first code to this.

import pandas as pd
import requests
from bs4 import BeautifulSoup

url_cntr = 'https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_population'
t = requests.get(url_cntr)
html_content = t.content
html_soup = BeautifulSoup(html_content, 'html.parser')
sov_tables = html_soup.find('table', class_="wikitable sortable")

At this point you have the table needed in sov_tables.
Now want to use Pandas with pd.read_html(),in this case you could also only used this method to get table and drop all over.

To bring sov_tables into pandas,it need to be file object or string.
So can use str()

df = pd.read_html(str(sov_tables))
df = df[0]
df

It also get easier if you use Jupyter Notebook,then the table also look nice.

At this point you can continue with task,need convert to columns to right format int,datetime..ect