The supplied bar chart illustrates the data concerning the number of visitors to Barcelona, Lisbon, and Venice from 2016 to 2020. Overall, it is obvious that the European city of Lisbon was less famous by visitors comparing with others, while the number of visitors to Venice and Barcelona fluctuated between the given period. During the initial two years, the number of visitors remained stable at almost over 20 million in Barcelona. Consequently, it surged to just over 23 million in 2018. However, there was a slight plunge in the figure of visitors to Barcelona by a narrow margin in 2019. Then, the figure dipped tremendously to under 5 million in 2020. According to Lisbon, there was a fluctuation in the number of visitors as it starts at over 8 million. Then it increased by a few million in 2017. In contrast to 2019, the number of visitors in 2018 was smaller by around 5 million. Following this, the graph demonstrates its nadir number in 2020 with almost 1 million. Furthermore, the data about Venice shown that the number of visitors went up constantly over the four years from 2016. Nevertheless, it dropped substantially by approximately 17 million in 2020. Ultimately, it is noticeable that the figures on the bar graph were not stable during the following five years. 
The supplied bar chart illustrates the data concerning the  
number
 of  
visitors
 to Barcelona, Lisbon, and Venice from 2016 to 2020.  
Overall
, it is obvious that the European city of Lisbon was less  
famous
 by  
visitors
 comparing with others, while the  
number
 of  
visitors
 to Venice and Barcelona fluctuated between the  
given
 period. During the initial two years, the  
number
 of  
visitors
 remained stable at almost  
over
 20  
million
 in Barcelona.  
Consequently
, it surged to  
just
  over
 23  
million
 in 2018.  
However
, there was a slight plunge in the figure of  
visitors
 to Barcelona by a narrow margin in 2019. Then, the figure dipped  
tremendously
 to under 5  
million
 in 2020. According to Lisbon, there was a fluctuation in the  
number
 of  
visitors
 as it  
starts
 at  
over
 8  
million
. Then it increased by a few  
million
 in 2017.  
In contrast
 to 2019, the  
number
 of  
visitors
 in 2018 was smaller by around 5  
million
. Following this, the graph demonstrates its nadir  
number
 in 2020 with almost 1  
million
.  
Furthermore
, the data about Venice shown that the  
number
 of  
visitors
 went up  
constantly
  over
 the four years from 2016.  
Nevertheless
, it dropped  
substantially
 by approximately 17  
million
 in 2020.  
Ultimately
, it is noticeable that the figures on the bar graph were not stable during the following five years.