Modeling dataset in .rdf format turtle format

Question

I have this simple dataSet representing interenet users by age group and sex for the following years. I must model this dataset in open data format RDF and populate the model using the data from this datasets.

Question one: As a solutipn I created the following ./ttl file with the folloing schema with my User and TimePeriod class. Can you find any mistakes in the schema or propose a better way and better ontologies for representign it:

@prefix : <http://tanya.org/schema/internetusage/> .
@prefix : <http://xmlns.com/foaf/0.1/>. 
# other prefixes ommitted 

#Dimension - rows
 :User rdf:type foaf:Person;
   rdfs:subClassOf scovo:Dimension;
   dc:title "Internet user, English region and Wales".

 :AgeGroup a rdfs:Property; 
   rdfs:domain InternetUser.         
     
#Dimensions - columns
 :TimePeriod rdf:type owl:Class;
   rdfs:subClassOf scovo:Dimension .

The second task was populating the model with data. I created a seconf .ttl file

@prefix : <http://tanya.org/data/internetusage/> .
@prefix internetusage: <http://tanya.org/schema/internetusage/> .

:2013 rdf:type internetusage:TimePeriod. 
:2014 rdf:type internetusage:TimePeriod. 
:2015 rdf:type internetusage:TimePeriod. 

:16_24_Male rdf:type internetusage:User;
   foaf:gender "male"; 
   internetusage:ageGroup "16-24";
     
      
:16_24_Female rdf:type internetusage:User;
   foaf:gender "female"; 
   internetusage:ageGroup "16-24"

# Other agegroups ommitted for brevity

#Dataset
:ds1 rdf:type scovo:Dataset;
     dc:title "Some title";
     scovo:datasetOf :ds1_1_1;
     scovo:datasetOf :ds1_1_2;
     scovo:datasetOf :ds1_1_3;
     scovo:datasetOf :ds1_2_1;
     scovo:datasetOf :ds1_2_2;
     scovo:datasetOf :ds1_2_3;
     scovo:datasetOf :ds1_3_1;
     scovo:datasetOf :ds1_3_2;
     scovo:datasetOf :ds1_3_3;
     scovo:datasetOf :ds1_4_1;
     scovo:datasetOf :ds1_4_2;
     scovo:datasetOf :ds1_4_3;
         . 
:ds1_1_1 rdf:type scovo:Item; 
     rdf:value 3,593;
     scovo:dataset :ds1; 
     scovo:dimension :16_24_Male 
     scovo:dimension :2013.      
 
:ds1_1_2 rdf:type scovo:Item; 
     rdf:value 3,590;
     scovo:dataset :ds1; 
     scovo:dimension :16_24_Male 
     scovo:dimension :2014.       

:ds1_1_3 rdf:type scovo:Item; 
     rdf:value 3,638;
     scovo:dataset :ds1; 
     scovo:dimension :16_24_Male 
     scovo:dimension :2015.  
    
:ds1_2_1 rdf:type scovo:Item; 
     rdf:value 3,482;
     scovo:dataset :ds1; 
     scovo:dimension :16_24_Female 
     scovo:dimension :2013.       

As you see here I have a dataset - 4 rows, 4 columns. Do you find any mistakes In the instances I have created. For example

:2013 rdf:type internetusage:TimePeriod. 

Should it be declared only once or 4 times so I that I have an instance for each row?